Assessing Treatment Outcomes in Toenail Onychomycosis Clinical Trials

Abstract

Several oral and topical medications are available for the treatment of onychomycosis, a widespread fungal infection of the nail. Since efficacy criteria vary greatly among clinical trials for onychomycosis treatment, it is difficult for physicians to compare outcomes and determine the appropriate therapy for a given patient. The present analysis evaluates the efficacy criteria used in intention-to-treat clinical trials of itraconazole, terbinafine, and 8% ciclopirox nail lacquer, drugs approved by the US FDA for the treatment of onychomycosis.

Efficacy parameters often appear to use subjective assessment tools and may not include the actual size measurement of the affected target nail as an efficacy variable. Parameters, which assess both mycologic and clinical cure, are frequently omitted from clinical trials. Not surprisingly, clinical trials with stringent efficacy criteria, which assess both mycologic and clinical response/cure without use of subjective methods, appear to have the lowest rates for both therapeutic response and complete cure. Thus, an evaluation of treatment options for onychomycosis cannot solely compare success/failure rates in clinical trials, but requires a critical appraisal of the efficacy criteria utilized in those trials.